1. Field of the Invention
The present invention relates to a serial printer, and more particularly to a printer having a scroll print buffer and a printing method. Still more particularly, the present invention relates to a serial printer which uses a print head having a plurality of ink jet nozzles and permits printing two or more lines per scan of the print head or permits mounting of print heads of different nozzle structures with respect to a print color, and a printing method using such a printer.
2. Related Background Art
Serial printer have been widely used as compact and inexpensive printers. Particularly, ink jet printers have made great advancement as silent and high speed printers and improvement of various characteristics have been made. For example, as to print speed, an improvement of speed was attained by speeding up a scan velocity of a carriage which carries a head.
For low cost personal computers, because of provision of a color graphic environment, a low cost and high grade color printer has been desired. In this field, again, the ink jet printer has been attracting an interest as a preferable printer.
A prior art color printer is more expensive than a monochromatic printer because of the necessity of provision of three or four color print heads. Further, since the color printer optimizes the print grade and the processing time for the color printing, monochromatic printing by the color printer is inferior in print grade and print speed to that by the monochromatic printer.
A printer which exchanges the monochromatic print head and the color print head to print out a desired image with a high efficiency has been proposed. By using the monochromatic print head, a high image density is attained and the print speed is improved although color printing is not attained.
However, since the arrangement of the recording elements (nozzles) is different between the monochromatic print head and the color print head, a print buffer compatible to the both heads is desired.
On the other hand, in the serial printer, a technique to form one line (band) by a plurality of scans (hereinafter referred to as a fine mode) may be used to make banding less prominent. A sheet feed distance (sub-scan distance) therefor may be 1/2, 1/3 or 1/4 of a head width. A print buffer which is compatible to the fine mode is desired.
However, in the serial printer, time is necessarily lost before and after a print period by a carriage scan due to the acceleration and deceleration of the carriage. As a result, improvement of print speed by increasing the scan speed of the carriage has reached its limit.